1. Field of the Invention:
The present invention relates to automation of the manufacture of trouser closures for fly openings, and more particularly to a method of and an apparatus for forming element-free spaces or gaps in a continuous slide fastener chain at its portions corresponding to ends of successive fly strips sewn to the chain.
2. Prior Art:
In the manufacture of trouser closures for fly openings, a continuous slide fastener chain, to which a succession of fly strips is sewn end to end in substantially abutting relation with only a very small space between an adjacent pair of the fly strips, is fed to an intermittently operating device for forming element-free spaces or gaps in the slide fastener chain. To this end, it has been customary practice to detect ends of the successive fly strips in order to automatically control the feeding of the chain as well as the intermittent operation of the gap-forming device. Such end detection is achieved by first folding the fly strips about a line of stitching to expose a pair of intermeshed rows of coupling elements of the chain as the latter advances, then providing temporarily a substantially V-shaped space between confronting ends of two adjacent fly strips prior to the arrival of the confronting ends at the gap-forming device, and finally sensing the presence of the V-shaped space when the trailing end of a preceding one of the adjacent two fly strips passes the light beam of a photoelectric sensor. However, such trailing end detection system is not suitable in applications wherein the fly strips are sewn to the slide fastener chain at random spaced fashion. More particualarly, when an adjacent pair of such fly strips is sewn to the chain with a relatively large space between confronting ends of the fly strips, an element-free space or gap formed in the chain would extend across only the trailing end of a preceding one of the two fly strips and terminate short of the leading end of the succeeding fly strip. With the slide fastener chain having the thus formed element-free space, automated operation in subsequent processing is difficult to achieve.